Comparison of the bioavailability of cyanocobalamin from capsule and liquid dosage forms.

Comparative in vivo absorption of cyanocobalamin from two dosage forms, gelatin capsule and liquid, was studied. Forty-two subjects received simultaneous doses of cyanocobalamin in capsule and liquid form, labeled with cobalt-57 and cobalt-60, respectively. Excretion, a measure of absorption, was between 2 percent and 66 percent greater with the liquid form. In vitro dissolution studies showed that the capsules had a tendency to collapse into a stringy mass and to dissolve slowly.